User Guide

CCS Technical Documentation
Company confidential RH-20
Issue 1 10/2003 Nokia Corporation. Page 27
Troubleshooting diagram for GSM900 receiver
Phone in “Continuous” mode, AGC setting “12”
Figure 21: GSM900 receiver troubleshooting
A
pply –90dBm
942.46771MHz signal
from generator to
antenna connector
Osilloscope at RX_I
signal 170mVpp DC
offset 1.35***
Fre
q
uenc
y
67.7kHz
Note! Generator level can be set higher if
needed. Just note that levels will be different
in whole chain respectively.
Spectrumanalyzer:
A
ntenna Switch
output GSM900
–
88dBm
Spectrumanalyzer:
A
ntenna Switch
input –88dBm
Spectrumanalyzer:
HELGO inputs
GSM900 –89dBm
Oscilloscope
VANT_1…3 0V
Oscilloscope:Check
HELGO serial
interface (burst
mode
)
Oscilloscope:
VR1,3…6 2.7V
Check HELGO
serial interface
(burst mode)
* Spectrumanalyzer reading
with 1 kohm passive probe
(right value add +26dB)
A
ll spectrumanalyzer
reading values are
measured with 1 kohm
passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading
value is represented without
+26 dB compensation.
Spectrumanalyzer:
4G VCO output
3769.6MHz
~-30dBm*
Check HELGO
N500
Check
Baseband
Check
C809
Rx 900 chain
functional
Check
L809,L810
Check
Baseband
Synthesizer
troubleshooting
Check HELGO
N500
Check Antenna
Switch Z800
*** DC-level of RXI/RXQ in
continuous mode will
decrase slowly. The original
level can be restored by
rewriting gain set
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
N
o
No
No
No
No
No
Check SAW
filter output
Check SAW
Z809
Yes
No